Lamp construction.



G. A. MA-CBETH. LAMP CONSTRUCTION.

APPHCATION FILED mzc.23. 1914.

Patented Aug. '20, 1918.

1 4' .1230 jgy ya I specification.

GEORGEA. MACBETH," OF PITTSBURGH, PENNSYLVANIA,

ASSIGNOR TO MACIBETH-EVANS GLASS COMPANY: or r r'rsnuncn, PENNSYLVANIA,A CORPORATION or PENNSYL- yam LAMP CONSTRUCTION.

To all whom z'tmay concern:

Be it known that I, GEORGE A. MACBETH, a citizen of the United States,residing at Pittsburgh, *in the county of Allegheny and State ofPennsylvania, have invented certain new and useful Improvements in LampConstructions, of which the following is a The invention relates tolamps or lanterns, and particularly to those for use on vehicles and tothe lens thereof. It has for its pri- .mary"objects the provision of animproved.

construction wherein the light from the upper portion of the lens isdimmed; thepro- VlSlOIl of a construction of improved ap-" pearance,wherein the light from the upper portion of the lamp is refractedlaterally in a, plurality of directions,

light and .avoiding the blinding lare of light so objectionable toobservers along the path of travel of the vehicle; and the pro- Visionof a lens wherein the rays from the,

lower portion" of the lens are allowed to diverge and illuminate theroad in front of the vehicle. invention are illustrated, in theaccompanying drawings, wherei n v Figure 1 is a face view of the lens,Fig. 2 is a section on the line III-II of Fig. 1, Fig. 3 is adiagrammatic side elevation View indicatingthe application of theinvention to a lamp or lantern, Fig. 4'is an edge elevation of thelens'of Fig. 1, Fig. 5 is a seci'on on the line VV of Fi 1, and Figs. 6and 7 are vertical sections t rough modified formsof lens construction.

As indicated in Fig. 3, 1 is the lens, 2 is the lamp casing, and 3 isthe source of illumination, it being understood that the lens isapplicable to a number of different types of head lights or lanterns andthat the one shown in Fig. 3 is merely illustrative of the method ofuse. p A'sindicated in Figs. 1,2 and 5, the lens is provided with anedge portion 4 to be held by the retaining devices of the lamp andcarries on one face a plurality of verti-- cal refracting ridges or ribs5, such ribs extending to 'a point below the horizontal difiusing theCertain embodiments of the passing through the upper Specification ofLetters Patent. Patented Aug, 20, 1918; Application filed December 23,1914. Serial No. 878,660. i

objectionable to observers at the front of I the vehicle and to thesides thereof. On the other hand the plain lower-portion 6 per-' I mitsthe rays '7 (Fig. 3) to diverge laterally .field of illumination closeto the vehicle is advantageous from the standpoint of the driver, andunobjectionable to'ob'servers at the sides of the vehicle, since therays are directed downwardly and are at a" level too low to reach theeyes of observers at the sides of the vehicle.

In ordervto secure a dimming efi'ect, the lens is preferably of glasscontaining asmall amount of coloring matter, preferably yellow, and asindicated in- Fig. 5 the upper portion 8 of the lens is made very muchthicker than the lower portion 6. The light from the'upper portion ofthe lens is therefore considerably dimmed rendering the headlightunobjectionable to observers along the path of the vehicle while thethinness of the portion 6 permits of a, bright illumination close to thevehicle where it will be of advantage to the driver and where it will beentirely unobjectionable to observers since the rays of light are at toolow a level invention in which there is no thickening of the upperportion 10 of the lens which carries-the ridges. The dimming efiect uponthe upper portion of this type of lens may be accomplished by using athin coat of coloring matter upon such portion, leaving. the lowerportion uncolored.

Fig. 7 illustrates another modification producing the same result as thefirst construction since the upper portion 9 is thickened, suchthickening occurring, however, on the reverse side of the glass. Ifdesired the additional glass might be otherwise distributed, the onlyrequirement being that the upper portion of the lens be thicker than thelower portion. It is immaterial which,

way the lens faces as the light efiect is substantially the same whenthe ribs face toward the source of illumination as when they face awayfrom it. In so far as the dimming effect due to the thickened andcolored glass is concerned, it is immaterial whether the refracting ribsare omitted or modified, and various changes in shape might obviously bemade to meet requirements.

What I claim is: 1. In combination in a lamp having a source ofillumination, a lens having its upper portion provided with verticalrefracting ridges and its lower portion plain, the upper portion of thelens carrying the ridges being thicker than the lower portion. 2. Incombination in a lamp having a source of illumination, a lens having itsupper portion of poorer light conducting capacity than the lower portionand having imposed thereon vertical 'refracting ridges which stillfurther reduce the light conducting capacity of the upper portion, the

lower portion of the lens being plain.

3. In combination in a lamp having a source of illumination, a lenshaving its upper portion'thicker than the lower por- 1 tion and havingimposed thereon means for diffusing the light, the lower portion of thelens being plain.

4. In combination in a lamp having a source of illumination, a lenshaving its upper portion of poorer light conducting capacity than thelower portion and having imposed thereon light diffusing means, the saidlower portion being'plain.

5. In combination in a lamp ihaving a GEO. Al. GBETH.

Witnesses:

JEROME E. Germs, H. S. Forum.

